There have been various designs for metal roofing shingles. These metal shingles typically attempt to replicate the aesthetic properties of traditional slate and cedar shingles while maintaining a degree of weather resistance expected with steep slope roofing products. Numerous patents have been granted on variations of these shingles, all of which attempt to create a substantially weather resistant metal shingle. Examples of these shingles can be found in U.S. Pat. No. 503,173 (Spahmer), U.S. Pat. No. 1,597,993 (Meurer), U.S. Pat. No. 1,743,206 (Fulenwider et al), U.S. Pat. No. 1,876,597 (Bennett), U.S. Pat. No. 5,469,680 (Hunt), and U.S. Pat. No. 5,832,686 (Plath et al).
The Spahmer patent discloses a single course shingle system where the opposing sides of each shingle are bent to create interlocking folds. Similarly, the top and bottom edge of each shingle are optionally bent to create interlocking folds. These shingles can then be assembled together by inserting the left edge of the shingle into the right edge of a previously installed shingle, while inserting the bottom edge into the top edge of a second previously installed shingle. The Spahmer patent discloses cutting the metal away in each of the corners to facilitate the process of creating folds along each edge. As a result, the corners of the shingles are susceptible to leakage in the event of severe weather conditions.
The Meurer patent discloses a single course shingle system where the left side of each shingle contains a tongue and the right side of each shingle contains a corresponding groove. Also present on the right side is a nailing strip designed so as to facilitate the installation process. In this patent, upper rows of shingles overlap the adjacent lower row, however, there is no interlocking mechanism between these two rows. As a result, the shingle is susceptible to leakage during severe weather conditions when water may be blown upwardly between the rows.
The Fulenwider patent discloses a single course shingle system where each shingle has opposing side edges that define corresponding shoulders, an underturned bottom edge and an overturned top edge. The overturned top edge is secured to a separately formed lock fastener. The slightly upturned lip of the lock fastener engages with the underturned bottom edge of the shingle directly above it. However, the lock fastener does not create an adequate seal and therefore the shingle is susceptible to leakage during severe weather conditions.
The Bennett patent discloses a single course shingle system where each shingle has opposing overturned and underturned side edges and an underturned bottom edge. A dam strip is used to secure the top edge of the shingle to the roof. Nail holes are provided in the flat surface of the shingle, where they are overlapped by the adjacent upper row of shingles. This system is susceptible to leakage through the nail holes and along the dam strip during server weather conditions, when water may be blown upwardly between the rows.
The Hunt patent discloses a single course shingle system where each shingle has an overturned top edge and a corresponding underturned bottom edge, which is used to interlock adjacent rows of shingles. A joint pan is placed under adjacent shingles. This joint pan guides any water that leaks through onto the lower row of shingles. However, this system is still susceptible to leakage when water is blown upwardly on the joint pan.
The Plath patent discloses a single course shingle system in which a gutter is formed in the trailing edge by creating an “s” shaped fold. The opposing edge is not folded and is inserted into the “s” shaped fold as the shingles are installed. The top edge is overturned, and the bottom edge has a corresponding underturn. The underturn at the bottom edge of each row of shingles interconnects with the overturn at the top edge of the lower row of shingles. The gutter helps guide water from between adjacent shingles down onto the outer surface of the lower row. However, the upper edge of the gutter is not folded, so leakage can occur if water is blown upwardly through the gutter during severe weather conditions.
Because of the inherent stiffness and formability of metal, creating a water-resistant metal shingle system that does not leak is a difficult undertaking. The installation of such a roofing system is also difficult. Each of the aforementioned patents attempts to solve some aspect of these shortcomings.